In power management, power generation and transmission are preferably efficiently carried out according to the power consumption of a load. If the power consumption of the load fluctuates, peak power may be excessive, increasing an electric utility rate. Furthermore, power supply may not cover the peak power. Power storage apparatuses may be used to average the power demand. Secondary batteries such as lithium ion batteries may be used as power storage apparatuses.
Patent Literature 1 discloses that a management apparatus for lithium ion batteries determines the status of charge and discharge of lithium ion batteries based on the measured values of a charge current to and a discharge current from the lithium ion batteries, the measured value of temperature, and information on power supply from a commercial power source, and calculates the state of charge corresponding to the remaining capacity of the lithium ion batteries.